3. A chef bought $17.01 worth of ribs and chicken. Ribs cost 1.89 per pound and chicken costs 0.90 per pound. The equation 0.9c + 1.89r = 17.01 represents the relationship between the quantities in this situation. Show that each of the following equations is equivalent to 0.9c + 1.89r = 17.01. Then, explain when it might be helpful to write the equation in these forms. a. c = 18.9-2.1r 10 b. r = -1c+9 21